Variables can only hold values of one type

A variable can only hold values of one type. For example, if a variable holds a Number value you cannot later use it to hold a String.

Example

Dim y As String
y = "hello"
'OK - the Len function expects a String argument
formula = Len (y)
'Error- y can only hold String values
y = #Jan 5, 1993#
'Error- y can only hold String values
y = Array ("a", "bb", "ccc")
'Error- the Sin function expects a Number argument
formula = Sin (y)

You can declare more than one variable per statement by separating their declaration by commas:

Dim x As Number, y as String, z as DateTime Range
x = 10 : y = "hello"
z = #Jan 1, 1999# To #Jan 31, 1999#